Fogged, direct-positive silver halide emulsion containing a color coupler and a heterocyclic mercaptan desensitizer

ABSTRACT

WHEREIN: R1 is hydroxyl or C1-C5 alkyl, R2 is hydrogen or C1-C5 alkyl, R3 is C1- C5 alkyl or aryl, A is a single bond or NH, B is a phenyl or diphenyl sulphone group in which the or both phenyl group(s) is (are) substituted with one or more nitro groups, and N IS 1, 2, OR 3. The desensitizing agents are highly compatible with color couplers.   A direct-positive photographic color element is described wherein the fogged silver halide emulsion comprises a color coupler and a desensitizing agent or precursor of such desensitizing agent wherein said desensitizing agent has one of the following general formulae, a tautomeric form thereof or is a corresponding disulphide :

United States Patent [1 1 Vanassche et a1.

[ Dec. 18, 1973 FOGGED, DIRECT-POSITIVE SILVER HALIDE EMULSIONCONTAINING A COLOR COUPLER AND A l-lETEROCYCLlC MERCAPTAN DESENSITIZER[75] Inventors: Willy Joseph Vanassche, Aartselaar;

Robert Joseph Pollet, Vremde; Hendrik Alfons Borginon, Mortsel; HermanAlberik Pattyn, Kapellen,

21 App]. No.: 269,861

[30] Foreign Application Priority Data July 30, 1971 Great Britain36017/71 [52] US. Cl 96/55, 96/100, 96/107, 96/108, 96/101 [51] Int. Cl.G03c 7/00, 0030 1/36, G030 1/28, G030 H40 [58] Field of Search 96/101,100,55, 96/107, 108

[56] References Cited UNITED STATES PATENTS 2,901,351 8/1959 Van Pee eta1. 96/101 3,501,305 3/1970 lllingsworth 96/108 Primary ExaminerNormanG. Torchin Assistant Eg1miner-W0n H. Louie, Jr. Attorney-Alfred W.Breiner [5 7] ABSTRACT A direct-positive photographic color element isdescribed wherein the fogged silver halide emulsion comprises a colorcoupler and a desensitizing agent or precursor of such desensitizingagent wherein said desensitizing agent has one of the following generalformulae, a tautomeric form thereof or is a corresponding disulphide Ris hydroxyl or C -C alkyl,

R is hydrogen or C -C alkyl,

R, is C,-C alkyl or aryl,

A is a single bond or NH,

B is a phenyl or diphenyl sulphone group in which the or both phenylgroup(s) is (are) substituted with one or more nitro groups, and

n is 1, 2, or 3.

The desensitizing agents are highly compatible with color couplers.

14 Claims, No Drawings FOGGED, DIRECT-POSITIVE SILVER HALKDJE EMULSIONCONTAINING A COLOR COUPLER AND A HETEROCYCLIC MERCAPTAN DESENSITIZER Thepresent invention relates to direct-positive silver halide emulsions andelements comprising fogged silver halide grains and color formingcouplers.

It is known that direct-positive images can be obtained with certaintypes of photographic silver halide reversal emulsions, which compriseuniformly fogged silver halide grains and photoelectron accepting ordesensitizing compounds.

It has further been described to introduce color forming couplingcompounds as used in conventional photographic silver halide emulsions,into such fogged silver halide emulsions comprising desensitizers.

However, most of the known desensitizers for use in direct-positivesilver halide emulsions are unsuitable for use in the presence of colorcouplers in that they are easily desorbed from the silver halide grainsby the color couplers, especially color couplers with watersolubilizingsulpho or carboxyl groups, which results in a reduction of thedirect-positive image formation and thus is a reduced photographic speedor in a complete inhibition of the direct-positive image formation.

It has now been found that desensitizing agents corresponding to one ofthe following general formulae or a tautomeric form thereof halideemulsions comprising color forming couplers.

The above desensitizing agents were found to be fully compatible withcolor couplers in that they favourably resist desorption from the silverhalide grains by color forming couplers.

The desensitizing agents corresponding to the above general formulae arenot only suitable for use as such but it is also possible to use thecorresponding disulphides thereof or such desensitizing agent precursorcompounds e.g., compounds corresponding to the general formulae or atautomeric form thereof wherein the tautomeric hydrogen atom is replacedby a COX group in which X represents alkyl, aryl, aralkyl or a groupidentical to the diazine group linked to the carbonyl group of COX, by aSO Y group in which Y is alkyl, aryl or aralkyl or by a COOZ groupwherein Z is alkyl or aryl v n I,

Therefore, in accordance with the present invention there is provided adirect-positive photographic emulsion comprising fogged silver halidegrains, a colorforming coupler and a desensitizing agent correspondingto one of the above general formulae, a corresponding disulphide thereofor such desensitizing agent precursor compound.

The present invention further provides a method of producingdirect-positive color images, which method comprises image-wise exposinga direct-positive element having prefogged silver halide grains andcomprising a desensitizing agent according to one of the above generalformulae, a corresponding disulphide thereof or such desensitizing agentprecursor compound, and developing said element by means of an aromaticprimary amino color developing agent in the presence of a co1orformingcoupler.

Representative examples of desensitizing agents for use according to thepresent invention can be found in British Pat. No. 796,873 filed Dec.10, 1954 by Gevaert Photo-Producten N .V.

The amount of desensitizing compounds used according to the presentinvention may vary within very wide limits. They are preferably used inamounts ranging from about mg to about 2 g per mole of silver halide.

Color forming coupling compounds are well known in the art of silverhalide photography. These compounds couple whilst forming dyes with theoxidized aromatic primary amino color developing agent, e.g.,p-phenylene diamine and derivatives thereof, such asN,N-dialkyl-p-phenylene diamines, e.g., N,N-diethyl-pphenylene-diamine,2-amino-5-diethylamino-toluene, 2 amino [N ethyl N (/3 methylsulphonyl.a mn L thxllaminql n N u y N sulpho butyl-p-phenylene diamine, etc.

These color-forming couplers include cyan-forming color couplers of thephenol or naphthol type, magenta forming color couplers of thepyrazolone or indazolone type and yellow forming open-chain reactivemethylene compounds containing the COCH -CO group, e.g.,benzoylacetanilide couplers. They include polymeric as well asnon-polymeric color couplers.

The color-forming couplers can be incorporated into the direct-positivephotographic silver halide emulsion any suitable technique, e.g., fromaqueous alkaline solutions or by techniques of the type shown in US.Pat. Nos. 2,186,849 of Gustave Wilmanns, Kreis Bitterfield, KarlKumetat, Alfred Friihlich, Wilhelm Scheider and Richard Brodersen issuedJan. 9, 1940; 2,269,158 of Michele Martinez issued Jan. 6, 1942;2,284,887 of Emil Vollenweider issued June 2, 1942; 2,304,939 of EmilVollenweider issued Dec. 15, 1942; 2,304,940 of Leopold D.Mannes andLeopold Godowsky Jr. issued Dec. 15, 1942; 2,322,027 of Edwin E. Julleyand Paul W. Vittum issued June 15, 1943 and 2,801,171 of Scheuring S.Fierke and Jonas John Chechak issued July 30, 1957, in British Pat. Nos.719,219 filed Nov. 9, 1955 by Kodak Ltd.; 1,098,594, 1,099,414,1,099,415, 1,099,416, 1,099,417 all filed Jan. 25, 1965 by Gevaert-AgfaN.V., in French Pat. No. 1,555,663, filed Oct' 20, 1967 by Gevaert-AgfaN.V. in Belgian Pat. No. 722,026 filed Oct. 9, 1968 by Gevaert-AgfaN.V., in German Pat. No. 1,127,714 filed Aug. 20, 1960 by PerutzFotowerke G.m.b.H. and in French Pat.

. No. 2,039,738 filed March 19, 1970 by Gevaert-Agfa aEPQiHsEQkQQWE e hs e s lt 2r ss lpqsi:

tion is not critical and may consist of any of the known silver halidessuitable for the formation of directpositive silver halide emulsions,e.g., silver bromide, silver chloride, silver chlorobromide, silverbromoiodide and silver chlorobromoiodide.

Especially suitable for use according to the present invention aredirect-positive silver halide emulsions, the silver halide grains ofwhich have an average grain size of less than about 1 micron. The silverhalide grains may be regular and have one of the commonly known shapes,e.g., cubic, octahedral or rhombohedral as described in British Pat.Application No. 14,224/71 filed May 1 l, 1971 by Gevaert-Agfa N.V. Theypreferably have a substantially uniform diameter.

Fogging of the silver halide emulsions may occur by exposure before orafter coating of the emulsion, to actinic radiation but preferablyfogging occurs by chemical means. Chemical fogging can be effected bychemical sensitization to fog and any of the usual chemical sensitizingmethods may be used. Fogging can be effected successfully by means ofreducing agents, e.g., hydrazine, hydroxylamine, tin(ll) salts such astin(ll) chloride, ascorbic acid, formaldehyde, thiourea dioxide alsocalled formamidine sulphinic acid, polyamines, phosphonium salts etc.The emulsions may also be sensitized chemically to fog by means of metalcompounds, the metal of which is more electropositive than silver, e.g.,compounds of gold, rhodium, platinum, palladium, iridium, and the like,e.g., gold (11]) chloride, potassium chloroaurate, and ammoniumchloropalladate. Fogging of the silver halide can be caused also by highpH and/or low pAg silver halide precipitating and digestion conditions.

The direct positive silver halide emulsions may further comprise allkinds of known emulsion ingredients, e.g., wetting agents, developmentaccelerators, optical brightening agents, hardeners, such asformaldehyde and mucochloric acid, stabilizers, spectral sensitizingdyes, which include cyanines, meroeyanines, complex (trinuclear)cyanines, complex (trinuclear) meroeyanines, styryls, and hemicyanines,etc.

Gelatin is preferably used as a vehicle for the silver halide but likein other silver halide emulsions the gelatin may be replaced wholly orpartly by other hydrophilic colloids, e.g., colloidal albumin, zein,agar-agar, polyvinyl alcohol, polyvinyl pyrrolidone, cellulose ethers,partly hydrolyzed cellulose esters, e.g., partly hydrolyzed celluloseacetate etc.

The emulsions may be coated on any of a wide variety of supports inaccordance with usual practice to provide light-sensitive silver halidematerials. The supports include glass, paper, baryta-coated paper,polyolefin-coated paper, e.g., coated with polyethylene andpolypropylene, which in order to promote adhesion of the emulsion may beelectron-radiated, film supports of cellulose acetate, celluloseacetatebutyrate, polyesters, e.g., polyethylene terephthalate,

etc.

The following examples illustrate the present invention.

EXAMPLE 1 A monodisperse, cubic direct-positive photographic silverbromoiodide emulsion (2.5 mole percent of iodide) having an averagegrain size of about 0.2 micron, was prepared under controlled pH, pAg,and temperature conditions during precipitation of the silver halide.The pH was maintained at about 5.5, the pAg at 8.2 and the temperatureat 45C. After adjustment of the pAg to 10. the emulsion was chill-set,shredded. and washed with cold water. 7 V

The emulsion was reductionand gold-fogged by adjustment of the pAg to5.3 and the pH to 7, by heating for 90 minutes at 60C and by theaddition of 30 mg of chloroaurate per mole of silver halide. Heating wascontinued for minutes at 60C whereupon the pAg was adjusted to 8.2 at35C.

The emulsion was divided into several samples and to each sample one ofthe desensitizing agents listed in the table below was added in anamount of 600 mg per mole of silver halide. To some samples amagentaforming color coupler of the formula t-CsHn C N m5 lLNHCo wasadded also in an amount of 4() g. per mole of silver halide.

The values of the speed obtained after exposure and conventionalblack-and-white or color processing are listed in the table below. Thevalues given for the speed are relative log exposure values. An increaseof these values by 0.30 means a doubling of the speed.

The above results show that pinacryptol yellow is completely desorbed bythe color coupler used, so that no direct-positive image is formedwhereas the desensitizing agent of the present invention resistsdesorption by the color coupler.

When the above desensitizing agent B was replaced by one of thefollowing desensitizing agent precursors C and D THQ-NO, N02 Hie-0 os-co l ll H /N HaC CH3 (C) and prepared as described hereinafter, it wasalso found that no substantial desorption by the color coupler occurred.

The desensitizing agent precursor C was prepared as follows Thedesensitizing agent B was dissolved in pyridine, whereupon benzoylchloride was added with cooling. The mixture was left standing for 12hours, whereupon the precipitate of pyridinium chloride was filtered offby suction and the filtrate poured out into water. The precipitateformed was filtered off by suction and was washed till free of pyridine.

Melting point 200C (with decomposition).

The desensitizing agent precursor D was prepared as follows Thecorresponding mercapto compound of compound D, which was prepared asdescribed in British Pat. No. 796,873 filed Dec. 10, 1954 by GevaertPhoto-Producten N.V., was dissolved in pyridine, whereupon benzenesulphochloride was added at 50C. The mixture was heated for 4 hours at70C and then poured into water. The precipitate formed was filtered offby suction and washed till free of pyridine.

Melting point 170C (with decomposition).

EXAMPLE 2 Example 1 was repeated with the difference that themagenta-forming color coupler was replaced by the cyan forming colorcoupler corresponding to the formula The values of the speed obtainedare listed in the following table.

TABLE Desensitizing Black-and-white processing Color procesagent in thesing in the without copresenpresence of color coupler cc of color lorcoupler coupler A 2.80 0 B 2.80 1.60 1.20

EXAMPLE 3 Example 1 was repeated with the difference that themagenta-forming color coupler was replaced by a yellow-forming colorcoupler corresponding to the formula 0 (CH1) GB:

The values of the speed obtainedare listed in the following table.

TABLE Desensi- Black-and-white processing Color procestizing withoutcoin the presence sing in the agent lor coupler of color couplerpresence of ler color coupler The above results show that even though byblackand white processing in the presence of a color coupler.pinacryptol yellow gives rise to the formation of a direct-positiveimage, no direct-positive image formation could be observed when theelement was color processed.

EXAMPLE 4 Example 1 was repeated with the difference that5-mnitrobenzylidene rhodanine was used as comparative desensitizingagent instead of pinacryptol yellow.

The values of the speed obtained are listed in the following table.

TABLE Dcsensi- Black-and-whitc processing Color procestizing sing in theagent without coin the prescnpresence of lor coupler cc of color colorcoupler coupler S-rn-ni troben- 2.80 0 0 zylidenerhodanine B 2.80 2.602.40

EXAMPLE 5 Example 4 was repeated with the difference that themagenta-forming color coupler was replaced by the color coupler of theformula The values of the speed obtained are listed in the foll. Adirect-positive photographic color element, which comprises uniformlyfogged radiation-sensitive silver halide, a color forming couplingproduct capable of forming a dye on coupling with an oxidized aromaticprimary amino color developing agent and a desensitizing agent or adesensitizing agent precursor wherein said desensitizing agent has oneof the following general formulae, a tautomeric form thereof, or is acorresponding disulphide R is hydroxyl or C,C alkyl,

R is hydrogen or C C alkyl,

R is C -C alkyl or aryl,

A is a single bond or NH,

B is phenyl or diphenyl sulphone group in which the or both phenylgroup(s) is (are) substituted with one or more nitro groups, and

n is 1, 2, or 3.

2. A direct-positive photographic element according to claim 1, whereinthe said desensitizing agent precursor is a compound corresponding toone of the general formulae of claim 1, or a tautomeric form thereof,wherein the tautomeric hydrogen atom is replaced by a COX group in whichX represents alkyl, aralkyl, aryl, or a group identical to the diazinegroup linked to the carbonyl group of COX, by a SO Y group in which Y isalkyl, aryl, or aralkyl, or by a COOZ group wherein Z is alkyl or aryl.

3. A direct-positive photographic element according to claim 1, whereinthe said desensitizing agent or desensitizing agent precursor is presentin an amount comprised between 100 mg and 2 g per mole of silver halide.

4. A direct-positive photographic element according to claim 1, whereinthe silver halide has been fogged uniformly by chemical means.

5. A direct-positive photographic element according to claim 4 whereinthe silver halide has been fogged uniformly by means of reducing agents.

6. A direct-positive photographic element according to claim 5, whereinsaid reducing agent is thiourea dioxide.

7. A direct-positive photographic element according to claim 4, whereinthe silver halide has been fogged uniformly by means of a gold compound.

8. A direct-positive photographic element according to claim 4, whereinthe silver halide has been fogged uniformly by means of a reducing agentand a gold compound.

9. A direct-positive photographic element according to claim 8, whereinsaid reducing agent is thiourea dioxide.

10. A direct-positive photographic element according to claim 1, whereinthe silver halide has been fogged uniformly by means of high pH and/orlow pAg silver halide precipitating and digestion conditions.

11. A direct-positive element according to claim 1, wherein the silverhalide has been fogged uniformly by means of a gold compound and by highpH and/or low pAg silver halide precipitating and digestion conditions.

12. A direct-positive photographic element according to claim 1, whereinthe silver halides of the emulsion have a substantially uniformdiameter.

13. A direct-positive photographic element according to claim 1, whereinthe silver halide grains have an average grain size of less than 1micron.

14. A method of producing a direct-positive image, which comprisesexposing image-wise to radiation a direct-positive element according toclaim 1, and developing the exposed material in a silver halidedeveloper comprising an aromatic primary amino color developing agent.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,"(79, 776 Dated December 18, 1973 Inventor(s) WilljiJoseph VANASSCHE ETAL It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Title page, in the'heading, [73] Assignee, "AFGA-Gevae-rt, N. V.,;

Mortse'l, Belgium" should read; Agfa-Gevaert, N. V. Mortsel, BelgiumColumn 1, lines 62 63, before "general" insert above f--.

Column 2, lines 34 35, "Z-arfpino- [N-ethyl-N-(fi-rnethylsulphonylamino)ethy1] amino-toluene" should read2-amino-5-{N-ethy1-N- -methylsulpho'nyl amino)ethyi] amino-tolueneColumn 3, line 13,

' Gev'aert-Agfa N. V. should x 'ead Agfa-Gevaert, N. V; Column 3,

' linesfi'? 68-, "temperature" should read thermal Signed and sealedthis 29th day of October 1974.

(SEAL) Attest: ,M cGOY Mo GIBSON ER. 0. SHALL DANN v Atresting 0fficerComisaioner-of Patents powso 0459) uscoMM-oc 00876-P69 9 .5. GOVIRNHEFT'IINTING O'I'CE 2 l0" 0-!6-83,

2. A direct-positive photographic element according to claim 1, whereinthe said desensitizing agent precursor is a compound corresponding toone of the general formulae of claim 1, or a tautomeric form thereof,wherein the tautomeric hydrogen atom is replaced by a -COX group inwhich X represents alkyl, aralkyl, aryl, or a group identical to thediazine group linked to the carbonyl group of -COX, by a -SO2Y group inwhich Y is alkyl, aryl, or aralkyl, or by a -COOZ group wherein Z isalkyl or aryl.
 3. A direct-positive photographic element according toclaim 1, wherein the said desensitizing agent or desensitizing agentprecursor is present in an amount comprised between 100 mg and 2 g permole of silver halide.
 4. A direct-positive photographic elementaccording to claim 1, wherein the silver halide has been foggeduniformly by chemical means.
 5. A direct-positive photographic elementaccording to claim 4 wherein the silver halide has been fogged uniformlyby means of reducing agents.
 6. A direct-positive photographic elementaccording to claim 5, wherein said reducing agent is thiourea dioxide.7. A direct-positive photographic element according to claim 4, whereinthe silver halide has been fogged uniformly by means of a gold compound.8. A direct-positive photographic element according to claim 4, whereinthe silver halide has been fogged uniformly by means of a reducing agentand a gold compound.
 9. A direct-positive photographic element accordingto claim 8, wherein said reducing agent is thiourea dioxide.
 10. Adirect-positive photographic element according to claim 1, wherein thesilver halide has been fogged uniformly by means of high pH and/or lowpAg silver halide precipitating and digestion conditions.
 11. Adirect-positive element according to claim 1, wherein the silver halidehas been fogged uniformly by means of a gold compound and by high pHand/or low pAg silver halide prEcipitating and digestion conditions. 12.A direct-positive photographic element according to claim 1, wherein thesilver halides of the emulsion have a substantially uniform diameter.13. A direct-positive photographic element according to claim 1, whereinthe silver halide grains have an average grain size of less than 1micron.
 14. A method of producing a direct-positive image, whichcomprises exposing image-wise to radiation a direct-positive elementaccording to claim 1, and developing the exposed material in a silverhalide developer comprising an aromatic primary amino color developingagent.